Stimulatory effect of aerosil on algal growth

2002 ◽  
Vol 48 (2) ◽  
pp. 170-175
Author(s):  
Bogdan I Gerashchenko ◽  
Igor I Gerashchenko ◽  
Toshikazu Kosaka ◽  
Hiroshi Hosoya
Keyword(s):  
Stationary Phases ◽  
Algal Growth ◽  
Life Cycles ◽  
Growth Patterns ◽  
Logarithmic Phase ◽  
Light Scatter ◽  
Cell Numbers ◽  
Colloidal Form ◽  
Unicellular Green Alga ◽  
Late Logarithmic Phase

Unicellular green alga represents not only a convenient model for its biochemical and physiological studies but also a sensitive system to test the effects of various environmental factors. Algae cells of two strains, SA-3 strain (exsymbiotic from Paramecium bursaria) and Chlorella vulgaris c-27, were asynchronously cultured in the presence of 0.01% Aerosil A-300. Aerosil effects on algae were monitored at logarithmic and stationary phases of their growth by flow cytometry and microscopic counting of algal numbers. The growth patterns of algae were evaluated by their forward light scatter versus fluorescence of endogenous chlorophyll (FL3-height) signal distributions. Although aerosil itself did not cause any direct effects on algal morphology, it affected the growth patterns and the numbers of algae of both strains. Their growth patterns were remarkably altered in the late logarithmic phase cultures (6-day cultures). However, a significant increase of cell numbers was found in the stationary phase cultures (9- and 12-day cultures). While C. vulgaris c-27 demonstrated an increase of cell numbers by approximately 11% in the 9- and 12-day cultures, the amounts of SA-3 cells in the 9- and 12-days cultures were increased by 16% and 35%, respectively. Our study shows aerosil in its colloidal form stimulates proliferation of algae mainly via an acceleration of their life cycles. The stimulatory effect of silica on the growth of algae, the mechanism of which remains to be clarified, might have a practical (e.g., ecological) interest for regulation of algal expansion.Key words: aerosil, cloned algae, growth, forward light scatter, chlorophyll fluorescence.

Use of Pediococcus acidilactici to Control Listeria monocytogenes in Temperature-Abused Vacuum-Packaged Wieners

1992 ◽  
Vol 55 (2) ◽  
pp. 98-103 ◽  
Author(s):  
ALAN J. DEGNAN ◽  
AHMED E. YOUSEF ◽  
JOHN B. LUCHANSKY
Keyword(s):  
Listeria Monocytogenes ◽  
Bacteriocin Production ◽  
Logarithmic Phase ◽  
Refrigerated Storage ◽  
Pediococcus Acidilactici ◽  
Bacteriocin Activity ◽  
Cell Numbers ◽  
Late Logarithmic Phase ◽  
Logarithmic Growth ◽  
Produce Acid

Pediococcus acidilactici JBL1095 (pediocin AcH producer) and P. acidilactici LB42 (bacteriocin nonproducer) were evaluated for the production of antilisterial compounds in packages of all-beef wieners. Commercially processed, freshly manufactured, unpackaged wieners were surface inoculated (ca. 105 CFU/g) as follows: (i) untreated control; (ii) a three-strain (Scott A, V7, 101M) mixture of Listeria monocytogenes; (iii) strain JBL1095; (iv) L. monocytogenes and strain JBL1095; and (v) L. monocytogenes and strain LB42. Wieners were vacuum packaged and cell numbers, pH, and bacteriocin activity within packages were determined following storage at refrigeration (4°C) or abuse (25°C) temperatures for 72 and 8 d, respectively. L. monocytogenes and pediococci survived in packages held at 4°C, but pediococci did not produce acid or pediocin during refrigerated storage. At 25°C, total numbers of L. monocytogenes (treatment ii) increased 3.2 log10 CFU/g and the pH of the fluid (exudate) within packages increased from 5.5 to 5.6. In contrast, L. monocytogenes survived but did not grow in packages inoculated with strain LB42 (treatment v), and was inhibited (average reduction of 2.7 log10 CFU/g) in packages inoculated with strain JBL1095 (treatment iv) during storage at 25°C for 8 d. The pH of exudate in packages inoculated with strains JBL1095 (treatment iv) or LB42 (treatment v) showed a similar decline (ca. 5.5 to 4.6). The onset of bacteriocin production coincided with early-logarithmic growth of JBL1095 (treatment iv) and continued into the late logarithmic phase. These data suggest that bacteriocinogenic pediococci can be used to control L. monocytogenes in temperature-abused, cook/chili meats.

scholarly journals Expression of a Mitochondrial Peroxiredoxin Prevents Programmed Cell Death in Leishmania donovani

2006 ◽  
Vol 5 (5) ◽  
pp. 861-870 ◽  
Author(s):  
Simone Harder ◽  
Meike Bente ◽  
Kerstin Isermann ◽  
Iris Bruchhaus
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Mitochondrial Membrane ◽  
Leishmania Donovani ◽  
Physiological Role ◽  
Logarithmic Phase ◽  
Insect Vector ◽  
Oxygen Species ◽  
Late Logarithmic Phase

ABSTRACT Leishmania promastigote cells transmitted by the insect vector get phagocytosed by macrophages and convert into the amastigote form. During development and transformation, the parasites are exposed to various concentrations of reactive oxygen species, which can induce programmed cell death (PCD). We show that a mitochondrial peroxiredoxin (LdmPrx) protects Leishmania donovani from PCD. Whereas this peroxiredoxin is restricted to the kinetoplast area in promastigotes, it covers the entire mitochondrion in amastigotes, accompanied by dramatically increased expression. A similar change in the expression pattern was observed during the growth of Leishmania from the early to the late logarithmic phase. Recombinant LdmPrx shows typical peroxiredoxin-like enzyme activity. It is able to detoxify organic and inorganic peroxides and prevents DNA from hydroxyl radical-induced damage. Most notably, Leishmania parasites overexpressing this peroxiredoxin are protected from hydrogen peroxide-induced PCD. This protection is also seen in promastigotes grown to the late logarithmic phase, also characterized by high expression of this peroxiredoxin. Apparently, the physiological role of this peroxiredoxin is stabilization of the mitochondrial membrane potential and, as a consequence, inhibition of PCD through removal of peroxides.

Growth and life histories in Nematoda with particular reference to environmental factors

Nematology ◽  
2003 ◽  
Vol 5 (5) ◽  
pp. 653-664 ◽  
Author(s):  
Brian Boag ◽  
Gregor Yeates
Keyword(s):  
Life Histories ◽  
Developmental Stages ◽  
Relative Size ◽  
Nematode Species ◽  
Life Cycles ◽  
Growth Patterns ◽  
Female Size ◽  
Lower Growth ◽  
Physical Support ◽  
Unifying Principles

AbstractTo seek unifying principles underlying growth patterns in the phylum Nematoda, the volume of successive developmental stages was determined from published measurements. Within some groups occupying fairly uniform, non-living habitats ( e.g. , Longidoridae, Mononchida, non-parasitic Rhabditida) growth patterns are similar, as are the sizes of both sexes. In aquatic Chromadorida and Monhysterida, females are commonly larger than males. Plant-parasitic groups vary in the relative size of the sexes; within Criconematoidea there is some reduction of males in Hemicyliophora but extreme reduction in Tylenchulus. Despite freeliving and parasitic cycles of Strongyloides showing differing growth in stages 2 to 4, females are similar in both cycles. The strongylid parasites of vertebrates studied have a bacterial-feeding external stage and have lower growth rates and achieve smaller female size than Ascardia with direct life cycles. In taxa for which data are available, the increase in volume between stages 1 and 2 was 0.4-53-fold; that between stages 2 and 3, typically, 1.8-2.9-fold but up to 8191-fold; between stages 3 to 4, 1.7-3.8-fold but up to 100-fold; and between stage 4 to female, typically, 1.1-42-fold but up to 918-fold. Complete data are available for few nematode species and there is no apparent consistent pattern in which taxa contain 'outliers' at particular stages. Many more data are required to assess the impacts of habitat texture, physical support, food supply and experienced temperature on nematode growth and size.

EXAMPLES OF NATURAL PHOTOGRAPHY FROM RENFREW COUNTY, ONTARIO

1967 ◽  
Vol 4 (4) ◽  
pp. 619-623 ◽  
Author(s):  
V. A. Saull
Keyword(s):  
Solar Radiation ◽  
Green Algae ◽  
Algal Growth ◽  
Growth Patterns ◽  
Field Site ◽  
Blue Green Algae ◽  
Photographic Records

Blue-green algae grow on water-covered carbonate bedrock in the Bonnechere River 2 miles (3.2 km) northwest of Eganville, Renfrew County, Ontario. The algal growth is sunlight-controlled, and the growth patterns are photographic records of present-day solar radiation at the field site. Equivalent patterns may be identifiable in ancient rocks, and if so, could be used to determine paleodirections, and possibly paleolatitudes as well.

scholarly journals MpeR Regulates themtrEfflux Locus in Neisseria gonorrhoeae and Modulates Antimicrobial Resistance by an Iron-Responsive Mechanism

2012 ◽  
Vol 56 (3) ◽  
pp. 1491-1501 ◽  
Author(s):  
Alexandra Dubon Mercante ◽  
Lydgia Jackson ◽  
Paul J. T. Johnson ◽  
Virginia A. Stringer ◽  
David W. Dyer ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Efflux Pump ◽  
Regulatory System ◽  
Logarithmic Phase ◽  
Free Iron ◽  
Content Type ◽  
Protein Encoding ◽  
Late Logarithmic Phase ◽  
Physiologic Parameters ◽  
Inner Membrane Protein

ABSTRACTPrevious studies have shown that the MpeR transcriptional regulator produced byNeisseria gonorrhoeaerepresses the expression ofmtrF, which encodes a putative inner membrane protein (MtrF). MtrF works as an accessory protein with the Mtr efflux pump, helping gonococci to resist high levels of diverse hydrophobic antimicrobials. Regulation ofmpeRhas been reported to occur by an iron-dependent mechanism involving Fur (ferric uptake regulator). Collectively, these observations suggest the presence of an interconnected regulatory system in gonococci that modulates the expression of efflux pump protein-encoding genes in an iron-responsive manner. Herein, we describe this connection and report that levels of gonococcal resistance to a substrate of themtrCDE-encoded efflux pump can be modulated by MpeR and the availability of free iron. Using microarray analysis, we found that themtrRgene, which encodes a direct repressor (MtrR) ofmtrCDE, is an MpeR-repressed determinant in the late logarithmic phase of growth when free iron levels would be reduced due to bacterial consumption. This repression was enhanced under conditions of iron limitation and resulted in increased expression of themtrCDEefflux pump operon. Furthermore, as judged by DNA-binding analysis, MpeR-mediated repression ofmtrRwas direct. Collectively, our results indicate that both genetic and physiologic parameters (e.g., iron availability) can influence the expression of themtrefflux system and modulate levels of gonococcal susceptibility to efflux pump substrates.

Effects of oestradiol and progesterone on the alkaline phosphatase activity of a human endometrial cancer cell-line

1980 ◽  
Vol 93 (1) ◽  
pp. 108-113 ◽  
Author(s):  
Mitsuaki Suzuki ◽  
Hiroyuki Kuramoto ◽  
Mieko Hamano ◽  
Hideo Shirane ◽  
Keiichi Watanabe
Keyword(s):  
Alkaline Phosphatase ◽  
Endometrial Cancer ◽  
Cell Growth ◽  
Cell Line ◽  
Growth Pattern ◽  
Cancer Cell Line ◽  
Hormonal Control ◽  
Logarithmic Phase ◽  
Adult Women ◽  
Late Logarithmic Phase

Abstract. The alkaline phosphatase (ALPase) activity of a human endometrial caner cell-line, established and designated as HEC-50-B in our laboratory, was investigated biochemically and histochemically in relation to its cell growth pattern and to the effects of the sex steroid hormones, oestradiol and progesterone. The ALPase activity increased sharply in the early stationary phase to reach an activity almost 2.5 times higher than that obtained in earlier stages of the culture. On administration of oestradiol to the culture medium, a sharp elevation of the ALPase activity was induced on an average of 2 days earlier (late logarithmic phase) than in the case of an ordinary culture (no hormone administration), without causing a notable change in cell growth pattern. It should be noticed, however, that progesterone at such a low concentration that had very little effect on cell growth in the culture could clearly prohibit the elevation of ALPase activity. This hormonal effect on the ALPase activity resembled that on the enzyme activity of the endometrium of adult women. The ALPase activity of both the cultured endometrial cancer cells and the endometrium was found to be a sensitive indicator of the effect of progesterone. It would be a useful tool for future study in elucidating the mechanism of hormonal control of the neoplasm.

scholarly journals Combination of flucloxacillin and gentamicin inhibits toxic shock syndrome toxin 1 production by Staphylococcus aureus in both logarithmic and stationary phases of growth.

1997 ◽  
Vol 41 (8) ◽  
pp. 1682-1685 ◽  
Author(s):  
P van Langevelde ◽  
J T van Dissel ◽  
C J Meurs ◽  
J Renz ◽  
P H Groeneveld
Keyword(s):  
Staphylococcus Aureus ◽  
Stationary Phase ◽  
Bacterial Growth ◽  
Toxic Shock Syndrome ◽  
Stationary Phases ◽  
Logarithmic Phase ◽  
Toxic Shock ◽  
Viable Bacteria ◽  
Static Effect ◽  
Toxic Shock Syndrome Toxin

Production of exotoxins by staphylococci and streptococci may lead to the development of toxic shock syndrome (TSS). Because clindamycin inhibits exotoxin production, its use has been advocated for the treatment of TSS. However, the bacteriostatic action of clindamycin might be a disadvantage for the treatment of overwhelming infections. We investigated the effects of flucloxacillin and gentamicin on exotoxin production, because incubation with these antibiotics combines bactericidal action with protein synthesis inhibition. Staphylococcus aureus during the logarithmic and stationary phases of growth was incubated with either clindamycin, flucloxacillin, or a combination of flucloxacillin and gentamicin at concentrations of 2 or 10 times the MIC. In logarithmic-phase cultures clindamycin had a static effect on bacterial growth. After incubation with flucloxacillin, either alone or in combination with gentamicin, a rapid and large reduction in the number of viable bacteria was demonstrated. In stationary-phase cultures none of the antibiotics significantly changed the number of viable bacteria. TSS toxin 1 (TSST-1) production during logarithmic-phase growth was inhibited by > or =95% by all antibiotics. In stationary-phase cultures, clindamycin, flucloxacillin, and the combination of flucloxacillin and gentamicin inhibited TSST-1 production by 95, 30, and 75%, respectively, compared with the level of exotoxin production in the controls. The present results indicate that clindamycin inhibits TSST-1 production and exerts bacteriostatic activity in both bacterial growth phases. Because the combination of flucloxacillin and gentamicin combines the inhibition of exotoxin production with high bactericidal activity at least in logarithmic-phase cultures, it should be considered an alternative to clindamycin for the treatment of exotoxin-mediated diseases, especially in patients with overwhelming infections.

ASSOCIATIVE GROWTH RELATIONSHIPS IN TWO STRAIN MIXTURES OF STREPTOCOCCUS LACTIS AND STREPTOCOCCUS CREMORIS1

1971 ◽  
Vol 34 (5) ◽  
pp. 236-240 ◽  
Author(s):  
M. S. Reddy ◽  
E. R. Vedamuthu ◽  
C. J. Washam ◽  
G. w. Reinbold
Keyword(s):  
Agar Medium ◽  
Growth Patterns ◽  
Initial Cell ◽  
Cell Numbers ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Tracer Methods

A recently described differential agar medium was used to study strain interactions in two-strain mixtures of Streptococcus lactis and Streptococcus cremoris. Two S. cremoris strains (ML4 and DR7) exhibited marked dominance over four S. lactis cultures. One S. cremoris strain, designated 1, showed excellent compatibility in all combinations. Streptococcus cremoris HP was progressively suppressed by all S. lactis strains. The associative growth patterns at 32 C and 21 C were similar irrespective of the initial cell numbers of the component strains. The technique described in this paper could be used in conjunction with phage tracer methods to investigate growth relationships among mixed strain lactic starters containing more than one strain each of S. lactis and S. cremoris.

AUTECOLOGY OF TWO AESHNA SPECIES (ODONATA) IN WESTERN VIRGINIA

1984 ◽  
Vol 116 (4) ◽  
pp. 567-578 ◽  
Author(s):  
Timothy G. Halverson
Keyword(s):  
Life Cycles ◽  
Growth Patterns ◽  
Juncus Effusus ◽  
Embryonic Diapause ◽  
Maturation Period ◽  
Larval Diapause ◽  
Early Evening ◽  
High Dispersal ◽  
Males And Females ◽  
Dead Plant

AbstractAeshna tuberculifera Walker and A. umbrosa Walker were studied in the Shenandoah Mountains, Rockingham County, Virginia for 5 years. Both species had 2-year life cycles. They passed the first winter in an embryonic diapause and the second in a larval diapause. Although A. umbrosa was slightly smaller and developed earlier in the year, growth patterns of the two species were similar. Adults emerged from mid-summer to mid-fall with a slight protandry. Sex ratio at emergence was equal in A. tuberculifera but slightly biased toward males in A. umbrosa. Individuals emerging later in the season tended to be smaller than those emerging earlier, and the decline in size was linear over time. The maturation period lasted 4–6 weeks. Poor recovery of marked teneral and breeding adults indicates either high mortality or high dispersal, but observed movement among ponds by marked breeding adults suggests high dispersal. Breeding males of both species defended entire ponds for short periods. Both males and females were present more frequently in the afternoon than during the morning or at mid-day. Females often oviposited in the late afternoon or early evening when males were usually absent from the ponds. A. tuberculifera used stems of Juncus effusus L. almost exclusively for oviposition, while A. umbrosa used a variety of dead plant or other material and rarely used J. effusus stems.

Growth and Phenotype of Low-Density Nasal Septal Chondrocyte Monolayers

2005 ◽  
Vol 133 (3) ◽  
pp. 417-422 ◽  
Author(s):  
David L. Hicks ◽  
August B. Sage ◽  
Barbara L. Schumacher ◽  
Robert L. Sah ◽  
Deborah Watson
Keyword(s):  
Tissue Engineering ◽  
Study Design ◽  
Stationary Phases ◽  
Initial Density ◽  
Growth Curves ◽  
Cell Number ◽  
Growth Patterns ◽  
High Density ◽  
Low Density ◽  
Small Tissue

OBJECTIVE: To analyze the growth patterns and differentiation of human septal chondrocyte monolayers of different seeding densities. STUDY DESIGN: Chondrocytes from 8 donors were plated at densities ranging from 20,000 cells/cm2 (high density) to 300 cells/cm2 (very low density). Confluency, cellularity, and glycosaminoglycan content were determined from days 1 to 15. RESULTS: Confluency was attained at 5.8, 8.3, 11.0, and 14.8 days for high-, intermediate-, low-, and very low-density monolayers, respectively ( P >0.001). Regression growth curves showed typical lag, logarithmic, and stationary phases. Confluent monolayers attained similar cellularity (power = 0.94) and differentiation (power = 0.88), regardless of initial density. CONCLUSIONS: Human septal chondrocyte monolayers reach confluency from very low initial densities. Growth patterns, cellularity, and differentiation are similar to other starting densities. SIGNIFICANCE: Very low-density monolayers expanded cell number 838-fold in 1 passage and therefore are sufficient for tissue-engineering purposes. This is important because of the requirement of maintaining differentiation and the limitation of small tissue harvest specimens.

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